1. Field of the Invention
The present invention relates to a printing system, a print preview method, a program, a printer driver, and a preview method using a printer driver, having a capability of previewing an image to be printed on paper in accordance with print data produced by application software.
2. Description of the Related Art
It is known to use a print preview function to display, on a screen of a host computer, an image of data which may include characters and graphical image to be printed, before the data is actually printed on paper, so that a user can know how the data will be printed. This print preview function allows the user to check the image to be printed and to perform a re-edit until a satisfactory layout has been achieved.
Many applications have a print preview function. On the other hand, the performance and functions of printer drivers have been improved, and a recent printer driver has a capability of modifying a layout. Thus, there has arisen a need for a printer driver capable of previewing data after the layout is modified. In a case in which previewing is performed using a printer driver, print data which may include characters and graphical data converted (rasterized) into a bitmap form and displayed on a screen before the bitmap data is transmitted to a printer.
In the case of a printer having a high resolution, print data is converted into high-resolution bitmap data. Therefore, if the resultant high-resolution bitmap data is displayed, a preview process takes a long time. In some cases, preview bitmap data is saved in a file so that it can be used when the preview image is displayed again. However, such a file becomes very large in size. To avoid the above problem, it is required to produce bitmap data with a low resolution for use of preview. However, when the spooling function provided in a system is used, it is impossible to change the resolution after spooling is performed. Therefore, to change the resolution after spooling is performed, it is necessary to develop a special spooling function capable of changing the resolution and add it to the spooling function of the system. However, this method needs an additional cost for the development of the special spooling function. Besides, in this method, the two-stage spooling causes degradation in performance and affinity for an OS (Operating System).
In a case in which a high-resolution printer is used, data is converted into bitmap data with a high resolution. If such high-resolution bitmap data is used in previewing of a print image, preview processing will take a long time. When previewing is performed using low-resolution bitmap data to avoid the above problem, if the image displayed according to the low-resolution bitmap data is enlarged, jaggies become conspicuous.
Jaggies can be reduced if the resolution of the preview bitmap data is changed depending on the size of the preview image displayed on the screen. However, in this method, it is necessary to produce bitmap data each time the scaling factor is changed, and thus additional processing time is needed.
In a case in which rasterizing is performed into a resolution different from the resolution of spooled data, it is necessary to perform a coordinate transformation. In this case, depending on the difference between the resolution of spooled data and the rasterization resolution, the width of lines which should be displayed with the same width, can differ depending on the location of lines.
For example, as shown in FIG. 13, if an image including lines with the same width and numeric characters with the same width is rasterized into a resolution different from the spooled resolution, the line width in the resultant preview image can be different depending on the locations of lines and numeric characters can have large jaggies.